The present invention pertains to an atomizing nozzle for a burner, especially for a heater that can be used on a vehicle, comprising a first flow guide element that provides a first flow guiding surface and has an atomizing lip in an axial end area in relation to a central axis of the nozzle, a second flow guide element defining a first flow space area leading to the atomizing lip together with the first flow guide element, as well as a fuel feed device in the second flow guide element for applying fuel through the first flow space area onto the flow guide surface of the first flow guide element.
A burner that can be used in gas turbines is known from EP 0 910 776 B1. Fuel is injected in this burner by an injection nozzle onto a flow guide surface of a flow guide element ending in an atomizing lip. The fuel leaving the injection nozzle under high pressure passes through a flow space area leading to the atomizing lip before it reaches the flow guide surface of the flow guide element for further distribution and for atomization. The fuel is released here from a surface of the atomizing nozzle, which has a surface normal (or a normal surface) that is essentially parallel to a central axis of the nozzle. The fuel stream, which is also directed partially radially, must be released under high pressure in order to ensure that it will be carried by the air stream before it reaches the flow guide surface of the flow guide element.
The feeding of fuel under high pressure is critical especially in the case of use in automobiles. The reason for this is that the fuel feed lines must be frequently led past components that have very high temperatures. The consequence of a leakage in the area of these lines would be that the fuel, which is under high pressure, would escape in the area of this leak and be possibly atomized. This entails the risk of an immediate inflammation of the fuel in the area of such leaks.
The object of the present invention is to improve an atomizing nozzle of this class such that it ensures reliable distribution or atomization of the fuel with high reliability of operation.
This object is accomplished according to the present invention by an atomizing nozzle for a burner, especially for a heater that can be used on a vehicle, comprising a first flow guide element, which provides a flow guide surface and has an atomizing lip in an axial end area in relation to the first flow guide element, a second flow guide element defining a flow space area leading to the atomizing lip together with the first flow guide element, as well as a fuel feed device in the second flow guide element for applying fuel through the first flow space area onto the flow guide surface of the first flow guide element.
Provisions are, furthermore, made according to the present invention for the fuel feed device to have at least one fuel feed channel section in the second flow guide element, which said fuel feed channel section is open toward a surface area of the second flow guide element, which has a surface normal radial component different from zero.
It is ensured in the present invention that the fuel is already discharged with a radial component from a fuel feed channel section, of which there is at least one, without the necessity of feed under high pressure. The risk that fuel particles would be carried in the air stream flowing through the flow space area without reaching the flow guide surface of the first flow guide element is thus essentially eliminated.
For example, provisions may be made for the second flow guide element to be tapered downstream of the opening area of the at least one fuel feed channel section in relation to the central axis of the nozzle.
However, it is also possible as an alternative to expand the second flow guide element downstream of the opening area of the at least one fuel feed channel section in relation to the central axis of the nozzle. The expanding configuration of the second flow guide element may be used, furthermore, to provide a fuel release lip at the second flow guide element downstream of the opening area of the at least one fuel feed channel section. The fuel being discharged from the fuel feed channel section consequently moves along the radially outwardly expanding surface of the second flow guide element, and reaches the fuel release lip while a predistribution is performed in the circumferential direction, and it is then moved farther from the fuel release lip in the radially outward direction to the flow guide surface of the first flow guide element.
Reliable transport of the fuel along the second flow guide element in the direction of the fuel release lip can be ensured by the surface normal in the surface area of the second flow guide element being directed essentially opposite a stream flowing through the first flow space area.
According to an especially advantageous embodiment, the most uniform fuel feed possible can be achieved by providing a plurality of fuel feed channel sections in the second flow guide element, which are open toward respective surface areas of the second flow guide element at opening areas following each other in the circumferential direction in relation to a central axis of the nozzle. Furthermore, it is advantageous for the at least one fuel feed channel section to open into the surface area essentially in the direction of the surface normal.
To support the reliable transport of the amount of fuel being discharged by the second flow guide element in the radially outward direction, it is proposed that at least one deflecting element be provided to generate a swirling flow in the first flow space area. By providing a swirl in the air stream flowing through the first flow space areas, it is ensured that by generating corresponding centrifugal forces, the fuel particles being released by the second flow guide element are thrown radially outwardly in the direction of the flow guide surface of the first flow guide element.
To ensure a uniform and reliable atomization of the fuel fed to the first flow guide element in the atomizing nozzle according to the present invention, it is proposed that the first flow guide element define a second flow space area together with a third flow guide element.
According to another aspect, the present invention pertains to a heater with an atomizing nozzle. A fuel feed system can then be provided in this heater for feeding fuel to the at least one fuel feed channel section under a pressure of up to 2.0 bar and preferably up to 1.5 bar above the pressure prevailing in the first flow space area.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.